FR2549408A1 - ROBOT WRIST FOR DISTRIBUTION AND SCREW EMBEDDING - Google Patents

Abstract

THE SUBJECT OF THE PRESENT INVENTION IS A ROBOT WRIST FOR DISTRIBUTION AND EMBECTING OF SCREWS. THIS WRIST INCLUDES A FRAME IN WHICH A SPINDLE 4A-4B IS MOUNTED TO ROTATE, A SHAFT SHAFT 15 SLIDING IN THE SPINDLE AND CARRYING AT ITS END A HEAD 16 CLEAN TO CONTAIN A HEAD OF SCREW 18, MEANS TO DRIVE THE SPINDLE 4A-4B IN ROTATION, A CAM 27 TO MOVE THE AXIS LONGITUDINALLY IN THE SPINDLE, A CLAMP 50 WHICH IS INTENDED TO HOLD SCREW 19 TO BE FITTED AND IS MOVABLE RADIALLY WITH THE END OF THE AXIS D 'EMBECTAGE 15 CARRYING THE HEAD, FROM A POSITION IN WHICH THE SCREW IS IN THE AXIS OF THE SPINDLE, AND FROM THE MEANS FOR MOVING THE CLAMP 50.

Description

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  Robot wrist for dispensing and screw feeding.

  In general, a robot has a wrist for performing a given operation and is able to move its wrist to a defined coordinate point at which the operation

must be done.

  To make assemblies by screwing, it is necessary in a first operation to fix all the screws and to engage in the threads enough threads of the screws for the

  to fit; until now, this embroidering was done manually In a second operation, a machine simultaneously completes the screwing of all the screws according to a given torque.

  The present invention relates to a robot wrist that

  automatically ensures this encapsulation.

  The robot wrist according to the invention is characterized in that it comprises a frame in which a spindle is mounted rota15 tion, a keyed pinning pin sliding in the spindle and carrying at its end a head adapted to contain a head screw, means for driving the spindle in rotation, a cam for longitudinally displacing the axis in the spindle, a clamp which is intended to hold the screw to be put in place and is movable radially relative to the end of the spindle. embroidery pin carrying the head, from a position in which the screw is in

  the axis of the spindle, and means for moving the clamp.

  With a screw engaged in the gripper and the spindle being rotated while the end of the embossing spindle is moved away from the screw, the robot moves the wrist so as to bring the screw to the plumb of the hole. who should receive it The robot controls

  then the longitudinal displacement of the spindle axis whose head is engaged on the head of the screw and pushes this screw towards the hole by driving it in rotation The screw is thus embaled and partially screwed into the hole robot then controls the movement of the clamp that separates from the screw.

  The cam may be a cam-drum on which a finger integral in translation with the embroidering axis is supported by

elastic means.

  The wrist may have a wheel that carries a series of grippers at its periphery and can both pivot relative to the frame and move radially relative to the spindle, and means to move the wheel and rotate it after embroidering

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  With a screw, the robot moves the wheel away from the spindle and rotates it at an angle equal to the angular spacing between two adjacent clamps so that a new screw is ready to be spun.

  The gripper wheel may be pivotally mounted relative to a carriage which is radially movable relative to the spindle.

  In one embodiment of the invention, the means for driving the spindle in rotation are connected by a clutch to a shaft carrying the cam and to an intermediate shaft whose pivoting ensures both the displacement of the carriage and the pivoting 10. the gripper wheel Then it is enough for the robot to control

  the clutch at each screw feed.

  The intermediate shaft may, for example, drive an eccentric on which is pivotally mounted a sliding block in a groove of the carriage This block is advantageously housed with a cer tain clearance in its groove The withdrawal of the carriage so that of the wheel-gripper this takes place slightly after the screw has been screwed in. The means for pivoting the gripper wheel are advantageously controlled by the movement of the carriage back and forth. To this end, the wrist may comprise a ratchet wheel which is pivotally mounted relative to the carriage, which is rotatably connected to the wheel and cooperates with pawls carried respectively by

the frame and the cart.

  The wrist may comprise contactors detecting the arrival of the end-of-stroke pin and the pivoting of the intermediate shaft. It is possible with these detectors to detect

  the absence of screws or defective threads.

  An embodiment of the robot wrist according to the invention will now be described by way of nonlimiting example, with reference to the accompanying drawings, in which: FIG. 1 is a sectional view of the wrist; Figure 2 is a cross-sectional view along II-II of Figure 1; Figure 3 is a cross-sectional view along III-III of Figure 1; Figure 4 is a cross-sectional view along IV-IV of Figure 1 and shows the fastening means of the gripper wheel; Figure 5 is a cross-sectional view along V-V of Figure 1

  Figure 6 is a top view of the wrist.

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  As shown in the drawing the robot wrist according to the invention comprises a frame which is formed of four elements la, lb, lc and ld joined by bolts 2 and attached to a robot arm 3.

  A pin formed of two elements 4a and 4b screwed to each other, is rotatably mounted in the frame by means of bearings 5, 6 and 7 The element 4b of the pin is secured

  a pinion 8 which is engaged with a pinion 9 set on a shaft 10; it is rotatably mounted in bearings 11 and 10 12 carried by the elements lc and ld of the frame and the pinion 9 is also engaged with a pinion not visible in the drawing and cal 1 on the output shaft of a geared motor group 14.

  In pin 4a-4b is keyed sliding an axis 15 which

  door, at its lower part, a head 16 provided with a recess 15 17 adapted to contain the head 18 of a screw 19 At its upper part, the axis 15 is integral with a sleeve 20 which can slide in the part 4 a pin A spring 21 housed between the sleeve and the pin and bearing on the shoulders of these elements tends to move down the sleeve and the axis 15 which is integral therewith.

  The sleeve 20 is rotatably mounted by means of a bearing 22 in a cap 23 which is fixed on a rod 24

  slidably mounted vertically in bearings 25 and 26 carried by the frame.

  The rod 24 has a lateral shoulder 24a which is held in abutment by the spring 21 on a cam-drum 27 integral with a shaft 28 Celuici is rotatably mounted in the frame by means of bearings such as 29 and carries a pinion 30 which is here integral with the cam 27 and is engaged with a pi30 gnon 31 wedged on an auxiliary shaft 32 This shaft which is rotatably mounted in the frame by means of bearings-such

  33 carries a pinion 34 which is engaged with a pinion 35 integral with the driven member 36 of an electro-magnetic clutch.

  The driving element 37 of this clutch is integral with the shaft 10. Under these conditions, when the electromagnetic clutch is excited, the auxiliary shaft 32 pivots and pivots the drum cam 27 This releases the rod 24 which moves downwards by driving the sleeve 20 and the axis 15 The taper 16 lowers

while continuing to turn.

  A carriage 38 is slidably mounted on rails 3 e doors by the element 1b of the frame and directed towards the pin 4a-4b being

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  perpendicular to the axis of this spindle This carriage has a groove 40 whose direction is perpendicular to both the

  rails 39 and to the axis of the spindle 4a-4b (see Figure 2) In this groove is slidably mounted with a clearance 41 a block 42 which is articulated on an eccentric 43 wedged on the intermediate shaft 32.

  When this shaft rotates one turn, the carriage 38 and performs a movement back and forth which successively moves away and brings it closer to the pin 4 a-4 b.

  A hub 44 is secured to the carriage 38 by a screw 45 extending in a direction oblique to the axis of the pin 4a-4b.

  A ring 46 is rotatably mounted on the hub 44 by means of a bearing 47 which bears on a spacer ring 48.

  A wheel 49 which carries at its periphery a series of clamps 50 15 each adapted to receive a screw 19, is mounted on the ring 46 with the interposition of a ring 51 A caster 52, pivotally mounted in the wheel 49 around the ring 51 and maintained by a

  circlips 53, carries on its inner surface rails 54 able to move against the action of the return spring 55, the slats 56 20 which are slidably mounted in the thickness of the wheel 49 and can engage on a shoulder 57 of the ring 46.

  The ring 46 is secured to a conical pinion 58 against which the ring 51 abuts. The wheel 49 carries a series of pins 59 which are each arranged facing a clamp 50 and can engage in holes 60. gears 58, which solidarises the

  wheel 49 and pinion 58 in a determined angular position.

  The pinion 58 is engaged with a bevel gear 61 which is integral with a ratchet wheel 62 pivotally mounted on the carriage 38 and having a number of ratchets equal to the number of clamps provided at the periphery of the wheel 49 A lever 63 pivotally mounted at 64 on the element ld of the frame carries a pawl 65 engaged with the wheel 62 (see Figure 5) The lever 63 is hinged at 66 on one end of a spring 67 whose other end is pivotally mounted at 68 on a lever 69 This is mounted pivo35 at 70 on the carriage 38 and carries a pawl 71 engaged with

the wheel 62.

  We thus see that, * during a movement of return

  carriage 38, the ratchet wheel 62 pivots a tooth by driving the pinion 61 The movement is transmitted by the pinions 61 and 58 40 to the gripper wheel 49 which pivots by an angle equal to that se-

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pairing two clips 50.

  There are three position detectors 72, 73 and 74 forming detectors The contactor 72 is controlled by the cap 23 and is engaged when the axis 15 reaches its end of stroke The contactors 73 and 74 are controlled by two cams 75 and 76 which are fixed on the shaft 28 The cam 75 keeps the contactor 73 engaged at the start of the cycle, at which time the cam 76 does not act on the contactor 74 The contactor 73 is normally released before the contactor 72 is switched on. absence of screw, the shaft 15 reaches its stop position more quickly and is engaged before the release of the switch 72, which signals the fault If the thread of the screw is defective, the switch 74 is engaged by the cam 76 then that the switch 72 is not because the axis 15 is not in abutment, which signals this defect. The robot wrist that has just been described

following way.

  A wheel 49 loaded with screws has previously been put in place on the ring 46 and the motor 14 has been energized so that the pin 4a-4b is rotated; the axis 15 is main20 held in high position by the cam-drum 27 and a screw 19 is

  located in the axis of the head 16 The contactor 73 is closed.

  The robot then moves the wrist so that the screw 19 located in the axis of the head 16 is brought in line with the hole that must receive it. This position reached, it sends the starting signal of the cycle, which The auxiliary shaft 28 begins to rotate and the axis 15 descends, which ensures the encapsulation of the screw 16 and the beginning of its screwing. When the axis 15 reaches its bottom stop, the rotation continues and

the screw escapes the head 16.

  Moreover, the carriage 38 moves away from the spindle, which

  releases the screw 16; but because of the game 41, this movement occurs only after the screw is screwed.

  The movement of the carriage 38 rotates the ratchet wheel 62,

  therefore, the gripper wheel 49, so that a new screw 16 35 comes into the embroidering position.

  As the axis 15 has reached its bottom stop, the contactor 72 is closed, which controls the robot and ensures the movement of

  this one to a new hole to receive a screw.

  As the shaft 28 continues to rotate, the cam 27 progressively releases the shaft 15 which rises under the action of the spring 21.

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  At the same time, the carriage 38 returns to its initial position so that a new screw 18 is placed opposite the head 16.

  At this moment the shaft 28 has made a complete revolution The contactor 73 is then again actuated, which ensures the release of the clutch 3637 and the stop of the shaft 28 The robot wrist is thus ready for a new work cycle. As indicated above, if there is no screw in the clamp 50 located opposite the axis 15, the switch 73 is still actuated when the contactor 72 is closed, which signals this defect. screwing is indicated by the closing of the contactor 74 while the contactor 72 does not

is not, which stops the cycle.

  It goes without saying that the present invention should not be considered as limited to the embodiment described and shown, but covers, on the contrary, all variants.

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Claims (12)

  Robot wrist for dispensing and screw-wrapping characterized in that it comprises a frame in which a pin 4a-4b is rotatably mounted, a keyway 15 keyed sliding in the spindle and bearing its end a head 16 5 adapted to contain a screw head 18, means for driving the spindle 4a-4b in rotation, a cam 27 for moving longitudinally axis in the spindle, a clamp 50 which is intended to maintain the screw 19 to set up and is movable radially with respect to the end of the embroidery pin 15 carrying the head, 10 from a position in which the screw is in   the axis of the spindle, and means for moving the clamp 50.   Wrist according to claim 1, characterized in that   the cam 27 is a cam-drum on which a finger 24 integral in translation with the pin 15 is supported by resilient means 21.   3 wrist according to claim 1 or 2, characterized in that it comprises a wheel 49 which carries a series of clamps 50 at its periphery, and can both rotate relative to the frame and is   move radially relative to the spindle, and means for moving the wheel and rotating it.   4 wrist according to claim 3, characterized in that the axis of the pivot axis of the wheel is oblique relative to the axis of the spindle.   Wrist according to claim 3 or 4, characterized in that the gripper wheel 49 is pivotally mounted relative to a carriage 38 which is radially movable relative to the spindle 4 a-4 b.   6 Wrist according to claim 5, characterized in that the means 14 for driving the pin 4 a-4 b in rotation are re30 linked by a clutch 36-37 to a shaft 28 carrying the cam 27 and to   an intermediate shaft 32 whose pivoting ensures both the displacement of the carriage 38 and the pivoting of the gripper wheel 49.   7 Wrist according to claim 6, characterized in that the intermediate shaft 32 entrains an eccentric 43 on which is pivotally mounted a block 42 sliding in a groove 40 of the trolley 38.   Wrist according to claim 7, characterized in that   The first block 42 is housed with a certain clearance in its groove 40. 8 2549408   Wrist according to one of Claims 5 to 8, characterized   in that the means for pivoting the gripper wheel 49   are controlled by the movement of the carriage 38 back and forth.   Wrist according to claim 9, characterized in that it comprises a ratchet wheel 62 which is pivotally mounted relative to the carriage 38, which is rotatably connected to the wheel 49 and cooperates with pawls 65 and 71 carried respectively by the frame and by the cart.   11 Wrist according to one of claims 6 to 10, characterized by contactors 72, 73 and 74 detecting the arrival of the axis   15 at the end of stroke and the pivoting of the intermediate shaft 32.